Residual Properties of 2,4,5‐T and Picloram in Sandy Rangeland Soils

Scifres, C. J.; McCall, H. G.; Maxey, Robert A.; Tai, H.

doi:10.2134/jeq1977.00472425000600010010x

Cited by 10 publications

(6 citation statements)

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“…Ranchers have favored picloram because it has a lasting soil residual of up to three years (Scifres et al. ) and targets spotted knapweed and leafy spurge while sparing the preferred native perennial bunchgrasses. We used three complimentary approaches.…”

Section: Introductionmentioning

confidence: 99%

“…Picloram is one of the most commonly used herbicides for invasive species management in U.S. rangelands, with 11 metric tons of the active ingredient applied between 2007 and 2011 (Wagner et al 2017). Ranchers have favored picloram because it has a lasting soil residual of up to three years (Scifres et al 1977) and targets spotted knapweed and leafy spurge while sparing the preferred native perennial bunchgrasses. We used three complimentary approaches.…”

Section: Introductionmentioning

confidence: 99%

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Strong indirect herbicide effects on mycorrhizal associations through plant community shifts and secondary invasions

Lekberg

Wagner

Rummel

et al. 2017

Ecological Applications

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Million of acres of U.S. wildlands are sprayed with herbicides to control invasive species, but relatively little is known about non-target effects of herbicide use. We combined greenhouse, field, and laboratory experiments involving the invasive forb spotted knapweed (Centaurea stoebe) and native bunchgrasses to assess direct and indirect effects of the forb-specific herbicide picloram on arbuscular mycorrhizal fungi (AMF), which are beneficial soil fungi that colonize most plants. Picloram had no effect on bunchgrass viability and their associated AMF in the greenhouse, but killed spotted knapweed and reduced AMF colonization of a subsequent host grown. Results were similar in the field where AMF abundance in bunchgrass-dominated plots was unaffected by herbicides one year after spraying based on 16:1ω5 phospholipid fatty acid (PLFA) and neutral lipid fatty acid (NLFA) concentrations. In spotted-knapweed-dominated plots, however, picloram application shifted dominance from spotted knapweed, a good AMF host, to bulbous bluegrass (Poa bulbosa), a poor AMF host. This coincided with a 63% reduction in soil 16:1ω5 NLFA concentrations but no reduction of 16:1ω5 PLFA. Because 16:1ω5 NLFA quantifies AMF storage lipids and 16:1ω5 PLFA occurs in AMF membrane lipids, we speculate that the herbicide-mediated reduction in host quality reduced fungal carbon storage, but not necessarily fungal abundance after one year in the field. Overall, in greenhouse and field experiments, AMF were only affected when picloram altered host quantity and quality. This apparent lack of direct effect was supported by our in-vitro trial where picloram applied to AMF mycelia did not reduce fungal biomass and viability. We show that the herbicide picloram can have profound, indirect effects on AMF within one year. Depending on herbicide-mediated shifts in host quality, rapid interventions may be necessary post herbicide applications to prevent loss of AMF abundance. Future research should assess consequences of these potential shifts for the restoration of native plants that differ in mycorrhizal dependency.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strong indirect herbicide effects on mycorrhizal associations through plant community shifts and secondary invasions

Lekberg

Wagner

Rummel

et al. 2017

Ecological Applications

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“…Small amounts of picloram leave treated areas in surface runoff water (4,5,7,8,19,21). However, little is known about what happens after it leaves the area (11,20,23).…”

Section: Introductionmentioning

confidence: 99%

Picloram Dissipation in a Small Southwestern Stream

Johnsen¹,

Warskow²

1980

Weed sci.

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Picloram (4-amino-3,5,6-trichloropicolinic acid) injected directly into a small, central-Arizona stream was lost by normal stream flow actions, such as the mixing of fast- and slow-moving water, and the interchange of surface and subsurface water in gravel and sand beds along the stream. Picloram was injected at a concentration of 6.26 ppmw; the maximum amount detected was 2.362 ppmw at 0.4 km downstream, 0.943 ppmw at 0.8 km, 0.316 ppmw at 1.6 km, 0.014 ppmw at 3.2 km, 0.001 ppmw at 6.4 km, and none further downstream. Picloram was detected near the limits of detection (0.001 to 0.004 ppmw) 2 days after injection at the 0.4-, 0.8-, and 1.6-km sites. In photodegradation tests, sunlight decomposed 57% of the picloram in containers after 8.8 h of exposure.

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“…Picloram dissipated faster at low than high application rates on all 3 soil types. Picloram applied on rangeland generally has dissipated rapidly with the highest concentration remaining in the top 15 cm of the soil profile (Scifres et al 1977). Picloram applied at 0.28 kg/ha or less often dissipated within 60 days (Bauer et al 1972;Scifres et al 1971aScifres et al , 1971b.…”

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confidence: 99%

Leafy Spurge Control and Herbicide Residue from Annual Picloram and 2,4-D Application

Lym¹,

Messersmith²

1987

Journal of Range Management

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Abstract:Annual application of picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) and picloram plus 2,4-D [(2,4-dichlorophenoxy) acetic acid] and biannual application of 2,4-D for 5 consecutive years was evaluated for leafy spurge (Euphorbia esula L.) control. The picloram treatments were evaluated for soil residue. The experiment was located at 2 sites in eastern North Dakota and 1 site in western North Dakota on various soil types. Picloram at 0.28, 0.42, and 0.56 kg/ha provided 48, 75, and 90% leafy spurge control after 4 annual treatments, respectively. Control increased to 85 and 91% when 2,4-D at 1.1 kg/ha was added to the annual treatment of picloram at 0.28 and 0.42 kg/ha, respectively. However, 2,4-D with picloram at 0.56 kg/ha did not increase leafy spurge control compared to picloram alone.Picloram did not accumulate in the upper 15 cm of the soil profile and generally was not detected above the 2 ppbw level 12 months following each annual application. Greater picloram residue was found deeper in sandy than clay soil and in soil with high compared to low organic matter. Picloram at 500 and 250 ppbw was required to reduce leafy spurge seedling emergence and subsequent survival by 50%, respectively. However, picloram at 125 ppbw reduced leafy spurge regrowth from root segments of 4 lengths to near zero. Picloram at 8 to 32 ppbw stimulated leafy spurge seedling emergence compared to the control. Annual application of picloram at low rates gradually controlled leafy spurge, but picloram soil residues were not high enough to control subsequent seed germination and shoot regrowth from roots.1 Manuscript accepted 24 September 1986. Page 2 of 12 Keywords:Herbicide interaction, Euphorbia esula L., HPLC.Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) is the most effective herbicide for control of leafy spurge (Euphorbia esula L.) (Lym and Messersmith 1985a). Picloram at 2.2 kg/ha has given 80% leafy spurge control 27 months after application in North Dakota and for 36 to 39 months in Wyoming (Alley et al. 1983). The cost of picloram at 2.2 kg/ha is often 50% or more of the total land value and 8 to 10 times higher than the cash rent value of pasture and rangeland (Johnson 1984). Thus, it often is not economical to control leafy spurge with high rates of picloram on large infestations in pasture and rangeland.

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Residual Properties of 2,4,5‐T and Picloram in Sandy Rangeland Soils

Cited by 10 publications

References 0 publications

Strong indirect herbicide effects on mycorrhizal associations through plant community shifts and secondary invasions

Strong indirect herbicide effects on mycorrhizal associations through plant community shifts and secondary invasions

Picloram Dissipation in a Small Southwestern Stream

Leafy Spurge Control and Herbicide Residue from Annual Picloram and 2,4-D Application

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